The objective of this Phase I study is to develop novel hydrogel-based tissue expanders that have delayed expansion with the capacity to be reshaped by the surgeon. Currently, plastic surgery routinely uses silicone balloon-type tissue expanders or self-inflating expanders. Balloon-type tissue expanders require multiple visits and exterior equipment to generate expansion. Current self-inflating expanders expand immediately which may damage sutures related to the implantation wound. Neither of these technologies has the capability to be easily reshaped at the time of surgery. Given the wide range of tissue shapes and sizes encountered in the human body, the ability to reshape the expander by the surgeon with scissors and scalpels is desirable. This study will initially focus on expanders for use in dental surgery; however the same principles can be utilized for other tissues. The proposed hydrogel- based tissue expander will utilize biodegradable cross-linkers to delay swelling for 2-3 weeks so that surrounding tissues may heal from implantation prior to expansion. For shaping the proposed expander should also be elastic and flexible. The properties to be optimized in this study will be delayed swelling and flexibility Specific Aim 1 is the synthesis and characterization of biodegradable cross-linkers. These cross-linkers will utilize a biodegradable spacer. The materials used for this spacer chemically react in the presence of water generating non-toxic degradents which are either metabolized or excreted from the human body by a variety of mechanisms. These spacer units will be end-capped with non-degradable cross-linker units which hold the polymer chains of the hydrogel together until degradation occurs, thus slowing the rate of swelling. Specific Aim 2 is the characterization of delayed swelling hydrogels generated using these biodegradable cross-linkers. These cross-linkers will be incorporated into existing hydrogel technology to generate delayed swelling hydrogels. These hydrogels will be tested to determine their swelling pressure, degradability, elastic properties and mechanical properties. Successful completion of this Phase I study will generate novel, delayed-swelling, hydrogel based, tissue expanders which do not suffer the drawbacks of current tissue expansion technologies. These tissue expanders will not swell until sufficient healing has occurred for tissue expansion. These tissue expanders will not require multiple visits utilizing exterior equipment such as pumps and valves. These tissue expanders will also be easily re-shapable by the surgeon to custom fit certain tissues using tools readily available such as scissors. Phase II development will focus on creating a marketable prototype and animal studies. The objective of this research is to generate re-shapable, delayed-expansion, hydrogel-based tissue expanders for use in dental and reconstructive surgery. These tissue expanders will overcome problems associated with current technology such as eliminating exterior equipment and allowing custom fitting of the expander to the tissue by the surgeon. This technology will reduce the incidence of morbidity associated with this surgery thus promoting general public health. [unreadable] [unreadable] [unreadable]